阅读说明：本技术 同步磁阻电机变磁链直接转矩控制系统及方法 (Synchronous reluctance motor variable magnetic linkage direct torque control system and method ) 是由 鲁文其 宗法鑫 郑东阳 俞志君 王浩亮 罗坚 王江 于 2021-07-06 设计创作，主要内容包括：本发明公开了一种同步磁阻电机变磁链直接转矩控制系统,包括第一减法器、速度PI调节器、第二减法器、磁链计算模块、第三减法器、转矩滞环模块、磁链滞环模块、电压矢量选择表、三相整流/逆变器、定子电压矢量计算模块、定子电流矢量计算模块、定子磁链和转矩估算模块、转速估算模块和同步磁阻电机。本发明还同时公开了利用上述装置进行的同步磁阻电机变磁链直接转矩控制的二种方法,分别为基于功率因数角的变磁链直接转矩控制方法和基于最优磁链角的变磁链直接转矩控制方法。本发明能够大幅度降低稳态时的转矩脉动和转速振动的同时提高电机运行时的功率因数,具有低振动性、更大转矩和高可靠性,尤其适用于船舶舰船等复杂工况场合。(The invention discloses a variable magnetic linkage direct torque control system of a synchronous reluctance motor, which comprises a first subtracter, a speed PI regulator, a second subtracter, a magnetic linkage calculation module, a third subtracter, a torque hysteresis module, a magnetic linkage hysteresis module, a voltage vector selection table, a three-phase rectifier/inverter, a stator voltage vector calculation module, a stator current vector calculation module, a stator magnetic linkage and torque estimation module, a rotating speed estimation module and the synchronous reluctance motor. The invention also discloses two methods for controlling the variable magnetic chain direct torque of the synchronous reluctance motor by using the device, namely a variable magnetic chain direct torque control method based on a power factor angle and a variable magnetic chain direct torque control method based on an optimal magnetic chain angle. The invention can greatly reduce the torque pulsation and the rotating speed vibration in the steady state, simultaneously improve the power factor of the motor in the operation, has low vibration, larger torque and high reliability, and is particularly suitable for complex working condition occasions such as ships and warships.)

1. Synchronous reluctance machine becomes direct torque control system of magnetic chain, its characterized in that: the synchronous reluctance motor comprises a first subtracter, a speed PI regulator, a second subtracter, a flux linkage calculation module, a third subtracter, a torque hysteresis module, a flux linkage hysteresis module, a voltage vector selection table, a three-phase rectifier/inverter, a stator voltage vector calculation module, a stator current vector calculation module, a stator flux linkage and torque estimation module, a rotating speed estimation module and a synchronous reluctance motor;

the input of the first subtracter is connected with the output of the rotating speed estimation module, the input of the speed PI regulator is connected with the output of the first subtracter, the input of the flux linkage calculation module is respectively connected with the output of the speed PI regulator and the output of the rotating speed estimation module, the input of the second subtracter is respectively connected with the output of the speed PI regulator, the output of the stator flux linkage and the output of the torque estimation module, the input of the torque hysteresis module is connected with the output of the second subtracter, the input of the flux linkage hysteresis module is connected with the output of the third subtracter, the input of the voltage vector selection table is respectively connected with the output of the torque hysteresis module, the output of the flux linkage hysteresis module, the output of the stator flux linkage and the output of the torque estimation module, the input of the stator voltage vector calculation module is respectively connected with the output of the voltage vector selection table, The output of the three-phase rectifier/inverter is connected, the input of the stator flux linkage and torque estimation module is respectively connected with the output of the stator voltage vector calculation module and the output of the stator current vector calculation module, the input of the rotating speed estimation module is respectively connected with the output of the stator voltage vector calculation module and the output of the stator current vector calculation module, the input of the three-phase rectifier/inverter is connected with the output of the voltage vector selection table, the input of the stator current vector calculation module is respectively connected with the output of the synchronous reluctance motor and the output of the three-phase rectifier/inverter, and the input of the synchronous reluctance motor is connected with the output of the three-phase rectifier/inverter.

2. The variable flux direct torque control system of a synchronous reluctance machine according to claim 1, wherein:

the flux linkage calculation module comprises an optimal flux linkage angle calculation submodule and a flux linkage calculation submodule based on the optimal flux linkage angle, the input of the flux linkage calculation submodule based on the optimal flux linkage angle is respectively connected with the output of the speed PI regulator and the output of the optimal flux linkage angle calculation submodule, and the output of the flux linkage calculation submodule based on the optimal flux linkage angle is used as the output of the flux linkage calculation module; the input of the optimal magnetic chain angle calculation submodule is connected with the output of the rotating speed estimation module.

3. The variable flux linkage direct torque control method based on the power factor angle by using the variable flux linkage direct torque control system of the synchronous reluctance motor according to claim 1, wherein:

step S101, two-phase actual current i under a three-phase coordinate system of the synchronous reluctance motor is measured through two-phase resistance sampling_aAnd i_bAnd output to the stator current vector calculation module;

step S102, the stator current vector calculation module calculates the two-phase actual current i under the three-phase coordinate system according to the input in step S101_aAnd i_bObtaining the alpha-axis current component i under the actual static two-phase coordinate system through Clarke transformation_αBeta axis current component i_βAnd the output is to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S103, the three-phase rectifier/inverter converts the DC side bus voltage value u_dcInputting the voltage vector to a stator voltage vector calculation module;

step S104, the stator voltage vector calculation module carries out calculation according to the input tubular state information S of each switch_a、S_b、S_cAnd the DC side bus voltage value u inputted in step S103_dcObtaining the alpha-axis voltage component u under the actual static two-phase coordinate system through Clarke transformation_αAnd a beta axis voltage component u_βAnd simultaneously output to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S105, the stator flux linkage and torque estimation module is based on the alpha axis current component i input in step S102_αBeta axis current component i_βThe α -axis voltage component u input in step S104_αAnd a beta axis voltage component u_βThe magnetic chain angle theta and the stator magnetic chain psi are obtained through calculation_sAnd estimating the torque T_e：

Wherein R is_sIs stator resistance, p is the pole pair number, psi_αIs a component of the stator flux linkage of the alpha axis psi in a two-phase stationary coordinate system_βIs a beta axis stator flux linkage component under a two-phase static coordinate system; then the magnetic chain angle theta is output to a voltage vector selection table, and the stator magnetic chain psi is output_sOutput to the third subtracter to estimate the torque T_eOutputting to a second subtracter;

step S106, the rotating speed estimation module carries out estimation according to the alpha-axis current component i input in the step S102_αBeta axis current component i_βThe α -axis voltage component u input in step S104_αAnd a beta axis voltage component u_βAnd calculating an estimated rotating speed omega and transmitting the estimated rotating speed omega to the first subtracter and the flux linkage calculating module respectively:

step S107, inputting the given motor rotating speed omega into a first subtracter;

step S108, the first subtractor calculates a speed difference Δ ω according to the given motor speed ω input in step S107 and the estimated speed ω input in step S106:

Δω＝ω*-ω (6)

then outputting the speed difference value delta omega to a speed PI regulator;

step S109, calculating the actual torque T of the motor by the speed PI regulator according to the speed difference delta omega input in the step S108_e ^*And output to the second subtracter and the flux linkage calculation module;

step S110, the flux linkage calculation module calculates to obtain a stator flux linkage given value psi^* _sAnd output to the third subtracter;

the implementation method of the flux linkage calculation module is a variable flux linkage direct torque control based on a power factor angle, and specifically comprises the following steps:

angle of power factorWhen the synchronous reluctance motor runs stably, the voltage equation of the motor in a steady state is as follows:

wherein u is_dIs the direct-axis voltage of the motor u_qIs motor quadrature axis voltage, R_sIs stator resistance, L_dIs a motor direct-axis inductor, L_qIs motor quadrature axis inductance, i_dFor direct shaft current of the motor, i_qFor motor quadrature current, X_qIs motor quadrature axis inductive reactance, X_dThe inductance is a direct axis inductance of the motor;

according to the inductive reactance formula:

the voltage equation (7) may be changed to:

the apparent power of the synchronous reluctance motor during operation is as follows:

S＝(u_di_d+u_qi_q)+j(u_qi_d-u_di_q) (10)

wherein j is an imaginary unit of the complex number;

in the formula (10), P is equal to u_di_d+u_qi_qRepresenting the active power of the synchronous reluctance machine, Q ═ u_qi_d-u_di_qRepresenting the reactive power of the synchronous reluctance machine:

substituting formula (9) into (11) yields:

the power factor equation is:

combining formula (12) and formula (13) to obtain:

to simplify the operation, let equation (14) Formula (14) is rewritten as follows:

actual torque T of synchronous reluctance motor in two-phase rotating coordinate system (d-q coordinate system)_e ^*The torque equation of (c) can be expressed as:

according to the analysis, the power factor angle of the motor is measuredAnd the motor direct axis current i in the formula (14) after the estimated rotation speed omega is determined_dQuadrature axis current i of motor_qHaving a defined functional relationship with respect to the actual torque T during steady-state operation of the machine_e ^*At a given time, i is obtained by combining (15) and (16)_d、i_qThe following were used:

then, according to the flux linkage equation (15) and the above equation (16), the dq-axis current is derived, and then the given value of the stator flux linkage is obtained as follows:

wherein psi_d、ψ_qRepresenting the projection components of the flux linkage on the d axis and the q axis;

step S111, the second subtracter is based on the actual torque T input in step S109_e ^*The estimated torque T input in step S105_eThe torque difference Delta T is obtained through calculation_eAnd the torque difference DeltaT is calculated_eOutput to torque hysteresis module:

ΔT_e＝T_e ^*-T (19)

step S112, the third subtracter determines the given value psi of the stator flux linkage according to the input of step S110^* _sStep 105 input stator flux linkage psi_sThe stator flux linkage difference value delta psi is obtained through calculation_sAnd then combining the stator flux linkage difference delta phi_sAnd outputting to a flux linkage hysteresis module:

Δψ_s＝ψ^* _s-ψ_s (20)

step S113, the torque hysteresis module is used for inputting the torque difference value delta T according to the step S111_eCalculating by a hysteresis comparator to obtain a torque control signal ST, and outputting the torque control signal ST to a voltage vector selection table;

step S114, the flux linkage hysteresis module calculates a flux linkage control signal SF through a hysteresis comparator according to the stator flux linkage difference value delta psi input in the step S112, and outputs the flux linkage control signal SF to a voltage vector selection table;

step S115, the voltage vector selection table calculates the tube state information S of each switch according to the section where the flux angle theta input in step 105 is located, the torque control signal ST and the flux control signal SF_a、S_b、S_cAnd output to the stator voltage vector meterA calculation module for calculating the tube state information S of each switch_a、S_b、S_cAnd controlling the switching state of the three-phase rectifier/inverter so as to realize the operation of the synchronous reluctance motor.

4. The optimal flux linkage angle-based variable flux linkage direct torque control method of the synchronous reluctance motor variable flux linkage direct torque control system according to claim 2, wherein:

step S201, two-phase actual current i under a three-phase coordinate system of the synchronous reluctance motor is measured through two-phase resistance sampling_aAnd i_bAnd output to the stator current vector calculation module;

step S202, the stator current vector calculation module calculates the two-phase actual current i under the three-phase coordinate system according to the input in step S201_aAnd i_bObtaining the alpha-axis current component i under the actual static two-phase coordinate system through Clarke transformation_αBeta axis current component i_βAnd the output is to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S203, the three-phase rectifier/inverter converts the DC side bus voltage value u_dcInputting the voltage vector to a stator voltage vector calculation module;

step S204, the stator voltage vector calculation module is used for calculating the tubular state information S of each switch according to the input tubular state information S of each switch_a、S_b、S_cAnd the DC side bus voltage value u inputted in step S203_dcObtaining the alpha-axis voltage component u under the actual static two-phase coordinate system through Clarke transformation_αAnd a beta axis voltage component u_βAnd simultaneously output to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S205, the stator flux linkage and torque estimation module depends on the alpha axis current component i input in step S202_αBeta axis current component i_βStep 204. the α -axis voltage component u is inputted_αAnd a beta axis voltage component u_βThe magnetic chain angle theta and the stator magnetic chain psi are obtained through calculation_sAnd estimating the torque T_e：

Wherein R is_sIs stator resistance, p is the pole pair number, psi_αIs a component of the stator flux linkage of the alpha axis psi in a two-phase stationary coordinate system_βIs a beta axis stator flux linkage component under a two-phase static coordinate system; then the magnetic chain angle theta is output to a voltage vector selection table, and the stator magnetic chain psi is output_sOutput to the third subtracter to estimate the torque T_eOutputting to a second subtracter;

step S206, the rotating speed estimation module carries out estimation according to the alpha-axis current component i input in the step S202_αBeta axis current component i_βStep 204. the α -axis voltage component u is inputted_αAnd a beta axis voltage component u_βAnd calculating an estimated rotating speed omega and transmitting the estimated rotating speed omega to the first subtracter and the flux linkage calculating module respectively:

step S207, inputting the given motor rotating speed omega into a first subtracter;

step S208, the first subtractor calculates a speed difference Δ ω according to the given motor speed ω input in step S207 and the estimated speed ω input in step S206:

Δω＝ω*-ω (6)

then outputting the speed difference value delta omega to a speed PI regulator;

step S209, the speed PI regulator calculates the actual torque T of the motor according to the speed difference delta omega input in the step S208_e ^*And output to the second subtracter and the flux linkage calculation module;

step S210, the flux linkage calculation module calculates to obtain a stator flux linkage given value psi^* _sAnd output to the third subtracter;

1) and the optimal flux linkage angle calculation submodule calculates to obtain an optimal flux linkage angle theta according to the input estimated rotating speed omega^*And the optimum flux linkage angle theta is determined^*And outputting the magnetic linkage angle to a magnetic linkage calculation submodule based on the optimal magnetic linkage angle, wherein the optimal magnetic linkage angle calculation submodule is realized by the following method:

stator flux linkage amplitude psi^* _sAnd the flux linkage angle θ is as shown in equation (21):

the direct-axis and quadrature-axis voltages of the synchronous reluctance motor are kept unchanged during stable operation:

the power equation is:

formula (22) is substituted for formula (23) and is obtained from the relationship between the stator flux linkage amplitude and the d and q axes:

the power factor equation is:

substituting the equations (24) and (25) into a power factor equation (26) to obtain a relation between the power factor and the estimated rotation speed omega and the flux linkage angle theta of the motor:

when the rotating speed reaches the steady state according to the formula (27), the corresponding magnetic linkage angle theta when the power factor is maximum is substituted into the formula (28) to obtain the optimal power angle theta^*Corresponding stator flux linkage amplitude:

2) and a flux linkage calculation submodule based on the optimal flux linkage angle calculates the actual torque T of the motor according to the input_e ^*Optimal flux linkage angle theta^*The stator flux linkage amplitude psi is obtained by calculation^* _sAnd the stator flux linkage amplitude psi^* _sOutputting to a third subtracter;

step S211, the second subtracter is based on the actual torque T input in step S209_e ^*The estimated torque T input in step S205_eThe torque difference Delta T is obtained through calculation_eAnd the torque difference DeltaT is calculated_eOutput to torque hysteresis module:

ΔT_e＝T_e ^*-T (19)

step S212, the third subtracter determines the given value psi of the stator flux linkage input in step S210^* _sStep 205 input stator flux linkage psi_sThe stator magnetism is obtained by calculationChain difference value delta psi_sAnd then combining the stator flux linkage difference delta phi_sAnd outputting to a flux linkage hysteresis module:

Δψ_s＝ψ^* _s-ψ_s (20)

step S213, the torque hysteresis module inputs the torque difference value delta T according to the step S211_eCalculating by a hysteresis comparator to obtain a torque control signal ST, and outputting the torque control signal ST to a voltage vector selection table;

step S214, the flux linkage hysteresis module calculates a flux linkage control signal SF through a hysteresis comparator according to the stator flux linkage difference value delta psi input in the step S212, and outputs the flux linkage control signal SF to a voltage vector selection table;

step S215, the voltage vector selection table calculates the tube state information S of each switch according to the interval where the flux angle theta input in step S205 is located, the torque control signal ST and the flux control signal SF_a、S_b、S_cAnd outputting the voltage vector to a stator voltage vector calculation module, and obtaining tubular state information S through each switch_a、S_b、S_cAnd controlling the switching state of the three-phase rectifier/inverter so as to realize the operation of the synchronous reluctance motor.

5. The control method according to claim 4, characterized in that:

based on the optimal flux linkage angle calculation submodule and the optimal flux linkage angle calculation submodule, the flux linkage direct torque control system of the synchronous reluctance motor is controlled, and the stator flux linkage amplitude psi^* _sThe given is carried out in two stages:

a constant flux linkage amplitude direct torque control strategy is adopted in the starting stage of the motor, the motor runs at a rated torque, and the maximum torque is output to overcome an inertial load and accelerate the motor to a given running state; when the motor runs to a steady state, calculating according to the formula (27) to obtain the corresponding maximum flux linkage angle theta at different given speeds, and further adopting a flux linkage direct torque control strategy based on the optimal flux linkage angle.

Technical Field

The invention relates to the field of motor control, in particular to a system and a method for controlling variable flux linkage direct torque of a synchronous reluctance motor.

Background

The direct torque control method of the synchronous reluctance motor has the advantages of simple structure, large starting torque, no dependence on other motor parameters except for the stator resistance, better robustness, no need of complex coordinate transformation and reduced calculation amount of the algorithm. The direct torque control does not control the current, but directly controls the flux linkage and the torque, has the rapid torque dynamic response capability, and is widely applied to the fields of fans, water pumps, air compressors and the like. However, in the conventional direct torque control, in order to realize the rapidity of the electromagnetic torque, the stator flux linkage amplitude is controlled to be a constant value, however, the stator flux linkage amplitude is not fixed and constant in the actual operation of the motor, in order to maintain the stator amplitude to be constant, an extra reactive excitation current component is necessary to maintain the stator flux linkage amplitude to be constant, and the introduction of the reactive current inevitably causes the loss of a control system to be increased, so that the power factor is reduced; the method has no fixed rule for the given stator flux linkage, and when the given flux linkage is too large or too small, the flux linkage and torque pulsation are aggravated to a certain extent, and when the given flux linkage is serious, the system cannot run. In the starting stage of the motor, the rotating speed is low, the magnetic linkage is in an undersaturation state due to large starting torque, and on the premise of ensuring that the control requirement is met, the current amplitude is inevitably increased, so that the torque pulsation is increased.

Accordingly, there is a need for improvements in the art.

Disclosure of Invention

The invention aims to provide a system and a method for controlling variable-flux direct torque of a synchronous reluctance motor, which are used for reducing torque pulsation and rotating speed vibration of the motor in a steady state and improving the reliability and the working efficiency of the motor.

In order to solve the above technical problem, the present invention provides a variable flux direct torque control system for a synchronous reluctance motor, comprising: the synchronous reluctance motor comprises a first subtracter, a speed PI regulator, a second subtracter, a flux linkage calculation module, a third subtracter, a torque hysteresis module, a flux linkage hysteresis module, a voltage vector selection table, a three-phase rectifier/inverter, a stator voltage vector calculation module, a stator current vector calculation module, a stator flux linkage and torque estimation module, a rotating speed estimation module and a synchronous reluctance motor;

the input of the first subtracter is connected with the output of the rotating speed estimation module, the input of the speed PI regulator is connected with the output of the first subtracter, the input of the flux linkage calculation module is respectively connected with the output of the speed PI regulator and the output of the rotating speed estimation module, the input of the second subtracter is respectively connected with the output of the speed PI regulator, the output of the stator flux linkage and the output of the torque estimation module, the input of the torque hysteresis module is connected with the output of the second subtracter, the input of the flux linkage hysteresis module is connected with the output of the third subtracter, the input of the voltage vector selection table is respectively connected with the output of the torque hysteresis module, the output of the flux linkage hysteresis module, the output of the stator flux linkage and the output of the torque estimation module, the input of the stator voltage vector calculation module is respectively connected with the output of the voltage vector selection table, The output of the three-phase rectifier/inverter is connected, the input of the stator flux linkage and torque estimation module is respectively connected with the output of the stator voltage vector calculation module and the output of the stator current vector calculation module, the input of the rotating speed estimation module is respectively connected with the output of the stator voltage vector calculation module and the output of the stator current vector calculation module, the input of the three-phase rectifier/inverter is connected with the output of the voltage vector selection table, the input of the stator current vector calculation module is respectively connected with the output of the synchronous reluctance motor and the output of the three-phase rectifier/inverter, and the input of the synchronous reluctance motor is connected with the output of the three-phase rectifier/inverter.

The invention relates to an improvement of a variable magnetic linkage direct torque control system of a synchronous reluctance motor, which comprises the following steps:

the flux linkage calculation module comprises an optimal flux linkage angle calculation submodule and a flux linkage calculation submodule based on the optimal flux linkage angle, the input of the flux linkage calculation submodule based on the optimal flux linkage angle is respectively connected with the output of the speed PI regulator and the output of the optimal flux linkage angle calculation submodule, and the output of the flux linkage calculation submodule based on the optimal flux linkage angle is used as the output of the flux linkage calculation module; the input of the optimal magnetic chain angle calculation submodule is connected with the output of the rotating speed estimation module.

The invention also provides a method for controlling by using the synchronous reluctance motor variable magnetic linkage direct torque control system, which is a variable magnetic linkage direct torque control method based on a power factor angle, and specifically comprises the following steps:

step S101, two-phase actual current i under a three-phase coordinate system of the synchronous reluctance motor is measured through two-phase resistance sampling_aAnd i_bAnd output to the stator current vector calculation module;

step S102, the stator current vector calculation module calculates the two-phase actual current i under the three-phase coordinate system according to the input in step S101_aAnd i_bObtaining the alpha-axis current component i under the actual static two-phase coordinate system through Clarke transformation_αBeta axis current component i_βAnd the output is to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S103, the three-phase rectifier/inverter converts the DC side bus voltage value u_dcInputting the voltage vector to a stator voltage vector calculation module;

step S104, the stator voltage vector calculation module carries out calculation according to the input tubular state information S of each switch_a、S_b、S_cAnd the DC side bus voltage value u inputted in step S103_dcObtaining the alpha-axis voltage component u under the actual static two-phase coordinate system through Clarke transformation_αAnd a beta axis voltage component u_βAnd simultaneously output to the stator flux linkageThe torque estimation module and the rotating speed estimation module are used for estimating the rotating speed;

step S105, the stator flux linkage and torque estimation module is based on the alpha axis current component i input in step S102_αBeta axis current component i_βThe α -axis voltage component u input in step S104_αAnd a beta axis voltage component u_βThe magnetic chain angle theta and the stator magnetic chain psi are obtained through calculation_sAnd estimating the torque T_e：

Wherein R is_sIs stator resistance, p is the pole pair number, psi_αIs a component of the stator flux linkage of the alpha axis psi in a two-phase stationary coordinate system_βIs a beta axis stator flux linkage component under a two-phase static coordinate system; then the magnetic chain angle theta is output to a voltage vector selection table, and the stator magnetic chain psi is output_sOutput to the third subtracter to estimate the torque T_eOutputting to a second subtracter;

step S106, the rotating speed estimation module carries out estimation according to the alpha-axis current component i input in the step S102_αBeta axis current component i_βThe α -axis voltage component u input in step S104_αAnd a beta axis voltage component u_βAnd calculating an estimated rotating speed omega and transmitting the estimated rotating speed omega to the first subtracter and the flux linkage calculating module respectively:

step S107, inputting the given motor rotating speed omega into a first subtracter;

step S108, the first subtractor calculates a speed difference Δ ω according to the given motor speed ω input in step S107 and the estimated speed ω input in step S106:

Δω＝ω*-ω (6)

then outputting the speed difference value delta omega to a speed PI regulator;

step S109, calculating the actual torque Te of the motor by the speed PI regulator according to the speed difference delta omega input in the step S108, and outputting the actual torque Te to the second subtracter and the flux linkage calculation module;

step S110, the flux linkage calculation module calculates to obtain a stator flux linkage given value psi^* _sAnd output to the third subtracter;

the implementation method of the flux linkage calculation module is a variable flux linkage direct torque control based on a power factor angle, and specifically comprises the following steps:

angle of power factorWhen the synchronous reluctance motor runs stably, the voltage equation of the motor in a steady state is as follows:

wherein u is_dIs the direct-axis voltage of the motor u_qIs motor quadrature axis voltage, R_sIs stator resistance, L_dIs a motor direct-axis inductor, L_qIs motor quadrature axis inductance, i_dFor direct shaft current of the motor, i_qFor motor quadrature current, X_qIs motor quadrature axis inductive reactance, X_dThe inductance is a direct axis inductance of the motor;

according to the inductive reactance formula:

the voltage equation (7) may be changed to:

the apparent power of the synchronous reluctance motor during operation is as follows:

S＝(u_di_d+u_qi_q)+j(u_qi_d-u_di_q) (10)

wherein j is an imaginary unit of the complex number;

in the formula (10), P is equal to u_di_d+u_qi_qRepresenting the active power of the synchronous reluctance machine, Q ═ u_qi_d-u_di_qRepresenting the reactive power of the synchronous reluctance machine:

substituting formula (9) into (11) yields:

the power factor equation is:

combining formula (12) and formula (13) to obtain:

to simplify the operation, let equation (14)

Formula (14) is rewritten as follows:

actual torque T of synchronous reluctance motor in two-phase rotating coordinate system (d-q coordinate system)_e ^*The torque equation of (c) can be expressed as:

according to the analysis, the power factor angle of the motor is measuredAnd the motor direct axis current i in the formula (14) after the estimated rotation speed omega is determined_dQuadrature axis current i of motor_qHaving a defined functional relationship with respect to the actual torque T during steady-state operation of the machine_e ^*At a given time, i is obtained by combining (15) and (16)_d、i_qThe following were used:

then, according to the flux linkage equation (15) and the above equation (16), the dq-axis current is derived, and then the given value of the stator flux linkage is obtained as follows:

wherein psi_d、ψ_qRepresenting the projection components of the flux linkage on the d axis and the q axis;

step S111, the second subtracter calculates the torque difference Delta T according to the actual torque Te input in step S109 and the estimated torque Te input in step S105_eAnd the torque difference DeltaT is calculated_eOutput to rotateMoment hysteresis module:

ΔT_e＝T_e ^*-T (19)

step S112, the third subtracter determines the given value psi of the stator flux linkage according to the input of step S110^* _sStep 105 input stator flux linkage psi_sThe stator flux linkage difference value delta psi is obtained through calculation_sAnd then combining the stator flux linkage difference delta phi_sAnd outputting to a flux linkage hysteresis module:

Δψ_s＝ψ^* _s-ψ_s (20)

step S113, the torque hysteresis module is used for inputting the torque difference value delta T according to the step S111_eCalculating by a hysteresis comparator to obtain a torque control signal ST, and outputting the torque control signal ST to a voltage vector selection table;

step S114, the flux linkage hysteresis module calculates a flux linkage control signal SF through a hysteresis comparator according to the stator flux linkage difference value delta psi input in the step S112, and outputs the flux linkage control signal SF to a voltage vector selection table;

step S115, the voltage vector selection table calculates the tube state information S of each switch according to the section where the flux angle theta input in step 105 is located, the torque control signal ST and the flux control signal SF_a、S_b、S_cAnd outputting the voltage vector to a stator voltage vector calculation module, and obtaining tubular state information S through each switch_a、S_b、S_cAnd controlling the switching state of the three-phase rectifier/inverter so as to realize the operation of the synchronous reluctance motor.

The invention also provides another method for controlling by using the synchronous reluctance motor variable magnetic linkage direct torque control system, which is a variable magnetic linkage direct torque control method based on an optimal magnetic linkage angle, and specifically comprises the following steps:

step S201, two-phase actual current i under a three-phase coordinate system of the synchronous reluctance motor is measured through two-phase resistance sampling_aAnd i_bAnd output to the stator current vector calculation module;

step S202, the stator current vector calculation module calculates the two-phase actual current i under the three-phase coordinate system according to the input in step S201_aAnd i_bObtaining the alpha-axis current component i under the actual static two-phase coordinate system through Clarke transformation_αBeta axis current component i_βAnd the output is to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S203, the three-phase rectifier/inverter converts the DC side bus voltage value u_dcInputting the voltage vector to a stator voltage vector calculation module;

step S204, the stator voltage vector calculation module is used for calculating the tubular state information S of each switch according to the input tubular state information S of each switch_a、S_b、S_cAnd the DC side bus voltage value u inputted in step S203_dcObtaining the alpha-axis voltage component u under the actual static two-phase coordinate system through Clarke transformation_αAnd a beta axis voltage component u_βAnd simultaneously output to a stator flux linkage and torque estimation module and a rotating speed estimation module;

step S205, the stator flux linkage and torque estimation module depends on the alpha axis current component i input in step S202_αBeta axis current component i_βStep 204. the α -axis voltage component u is inputted_αAnd a beta axis voltage component u_βThe magnetic chain angle theta and the stator magnetic chain psi are obtained through calculation_sAnd estimating the torque T_e：

Wherein R is_sIs stator resistance, p is the pole pair number, psi_αIs alpha-axis stator magnet under a two-phase static coordinate systemChain component, psi_βIs a beta axis stator flux linkage component under a two-phase static coordinate system; then the magnetic chain angle theta is output to a voltage vector selection table, and the stator magnetic chain psi is output_sOutput to the third subtracter to estimate the torque T_eOutputting to a second subtracter;

step S206, the rotating speed estimation module carries out estimation according to the alpha-axis current component i input in the step S202_αBeta axis current component i_βStep 204. the α -axis voltage component u is inputted_αAnd a beta axis voltage component u_βAnd calculating an estimated rotating speed omega and transmitting the estimated rotating speed omega to the first subtracter and the flux linkage calculating module respectively:

step S207, inputting the given motor rotating speed omega into a first subtracter;

step S208, the first subtractor calculates a speed difference Δ ω according to the given motor speed ω input in step S207 and the estimated speed ω input in step S206:

Δω＝ω*-ω (6)

then outputting the speed difference value delta omega to a speed PI regulator;

step S209, the speed PI regulator calculates the actual torque Te of the motor according to the speed difference delta omega input in the step S208 and outputs the actual torque Te to the second subtracter and the flux linkage calculation module;

step S210, the flux linkage calculation module calculates to obtain a stator flux linkage given value psi^* _sAnd output to the third subtracter;

1) and the optimal flux linkage angle calculation submodule calculates to obtain an optimal flux linkage angle theta according to the input estimated rotating speed omega^*And the optimum flux linkage angle theta is determined^*And outputting the magnetic linkage angle to a magnetic linkage calculation submodule based on the optimal magnetic linkage angle, wherein the optimal magnetic linkage angle calculation submodule is realized by the following method:

stator flux linkage amplitude psi^* _sAnd the flux linkage angle θ is as shown in equation (21):

the direct-axis and quadrature-axis voltages of the synchronous reluctance motor are kept unchanged during stable operation:

the power equation is:

formula (22) is substituted for formula (23) and is obtained from the relationship between the stator flux linkage amplitude and the d and q axes:

the power factor equation is:

substituting the equations (24) and (25) into a power factor equation (26) to obtain a relation between the power factor and the estimated rotation speed omega and the flux linkage angle theta of the motor:

when the rotating speed reaches the steady state according to the formula (27), the corresponding magnetic linkage angle theta when the power factor is maximum is substituted into the formula (28) to obtain the optimal power angle theta^*Corresponding stator flux linkage amplitude:

2) and the flux linkage calculation submodule based on the optimal flux linkage angle calculates the optimal flux linkage angle theta according to the input actual torque Te of the motor^*The stator flux linkage amplitude psi is obtained by calculation^* _sAnd the stator flux linkage amplitude psi^* _sOutputting to a third subtracter;

step S211, the second subtractor calculates a torque difference Δ T from the actual torque Te input in step S209 and the estimated torque Te input in step S205_eAnd the torque difference DeltaT is calculated_eOutput to torque hysteresis module:

ΔT_e＝T_e ^*-T (19)

step S212, the third subtracter determines the given value psi of the stator flux linkage input in step S210^* _sStep 205 input stator flux linkage psi_sThe stator flux linkage difference value delta psi is obtained through calculation_sAnd then combining the stator flux linkage difference delta phi_sAnd outputting to a flux linkage hysteresis module:

Δψ_s＝ψ^* _s-ψ_s (20)

step S213, the torque hysteresis module inputs the torque difference value delta T according to the step S211_eCalculating by a hysteresis comparator to obtain a torque control signal ST, and outputting the torque control signal ST to a voltage vector selection table;

step S214, the flux linkage hysteresis module calculates a flux linkage control signal SF through a hysteresis comparator according to the stator flux linkage difference value delta psi input in the step S212, and outputs the flux linkage control signal SF to a voltage vector selection table;

step S215, the voltage vector selection table calculates the tube state information S of each switch according to the interval where the flux angle theta input in step S205 is located, the torque control signal ST and the flux control signal SF_a、S_b、S_cAnd outputting the voltage vector to a stator voltage vector calculation module, and obtaining tubular state information S through each switch_a、S_b、S_cControlling the switching state of the three-phase rectifier/inverter to realize synchronous reluctance motorAnd (5) operating the machine.

Another method for controlling by using a synchronous reluctance motor variable flux linkage direct torque control system is an improvement of a variable flux linkage direct torque control method based on an optimal flux linkage angle:

based on the optimal flux linkage angle calculation submodule and the optimal flux linkage angle calculation submodule, the flux linkage direct torque control system of the synchronous reluctance motor is controlled, and the stator flux linkage amplitude psi^* _sThe given is carried out in two stages:

a constant flux linkage amplitude direct torque control strategy is adopted in the starting stage of the motor, the motor runs at a rated torque, and the maximum torque is output to overcome an inertial load and accelerate the motor to a given running state; when the motor runs to a steady state, calculating according to the formula (27) to obtain the corresponding maximum flux linkage angle theta at different given speeds, and further adopting a flux linkage direct torque control strategy based on the optimal flux linkage angle.

The invention has the following beneficial effects:

compared with the traditional direct torque control method, the variable magnetic linkage direct torque control system of the synchronous reluctance motor can greatly reduce torque pulsation and rotating speed vibration in a steady state and improve the power factor of the motor in operation, has low vibration and high reliability, is particularly suitable for complex working condition occasions such as ships and warships, and has the advantages of low cost, quick response and larger torque.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Fig. 1 is a block diagram of a variable flux linkage direct torque control system based on a power factor angle according to embodiment 1 of the present invention;

FIG. 2 is a functional block diagram of a stator current vector calculation module of FIG. 1;

FIG. 3 is a functional block diagram of a stator voltage vector calculation module of FIG. 1;

FIG. 4 is a flow diagram of a method of implementing the stator flux linkage and torque estimation module of FIG. 1;

FIG. 5 is a flowchart of a method for implementing the flux linkage calculation module of embodiment 1 in FIG. 1;

FIG. 6 is a schematic diagram of a hysteresis comparator of the torque hysteresis module of FIG. 1;

FIG. 7 is a schematic diagram of a hysteresis comparator of the flux linkage hysteresis module of FIG. 1;

FIG. 8 is a block diagram of a variable flux linkage direct torque control system based on an optimal flux linkage angle according to embodiment 2 of the present invention;

fig. 9 is a schematic diagram of a relationship between a power factor and a flux linkage angle in embodiment 2 of the present invention.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

examples 1,

The variable magnetic linkage direct torque control system based on the power factor angle of the synchronous reluctance motor is shown in fig. 1 and comprises a first subtracter, a speed PI regulator, a second subtracter, a magnetic linkage calculation module, a third subtracter, a torque hysteresis module, a magnetic linkage hysteresis module, a voltage vector selection table, a three-phase rectifier/inverter, a stator voltage vector calculation module, a stator current vector calculation module, a stator magnetic linkage and torque estimation module, a rotating speed estimation module and the synchronous reluctance motor;

the input of the first subtracter is connected with the output of the rotating speed estimation module, the input of the speed PI regulator is connected with the output of the first subtracter, the input of the flux linkage calculation module is respectively connected with the output of the speed PI regulator and the output of the rotating speed estimation module, the input of the second subtracter is respectively connected with the output of the speed PI regulator, the output of the stator flux linkage and the output of the torque estimation module, the input of the torque hysteresis module is connected with the output of the second subtracter, the input of the flux linkage hysteresis module is connected with the output of the third subtracter, the input of the voltage vector selection table is respectively connected with the output of the torque hysteresis module, the output of the flux linkage hysteresis module, the output of the stator flux linkage and the output of the torque estimation module, the input of the stator voltage vector calculation module is respectively connected with the output of the voltage vector selection table, The output of the three-phase rectifier/inverter is connected, the input of the stator flux linkage and torque estimation module is respectively connected with the output of the stator voltage vector calculation module and the output of the stator current vector calculation module, the input of the rotating speed estimation module is respectively connected with the output of the stator voltage vector calculation module and the output of the stator current vector calculation module, the input of the three-phase rectifier/inverter is connected with the output of the voltage vector selection table, the input of the stator current vector calculation module is respectively connected with the output of the synchronous reluctance motor and the output of the three-phase rectifier/inverter, and the input of the synchronous reluctance motor is connected with the output of the three-phase rectifier/inverter.

The method for controlling the variable magnetic linkage direct torque control system based on the power factor angle by utilizing the synchronous reluctance motor specifically comprises the following steps:

step 1, sampling and measuring two-phase actual current i of the synchronous reluctance motor under a three-phase coordinate system through two-phase resistors_aAnd i_bAnd outputs two-phase actual current i under three-phase coordinate system_aAnd i_bTo a stator current vector calculation module;

step 2, the stator current vector calculation module calculates the two-phase actual current i under the three-phase coordinate system according to the input in step 1_aAnd i_bAs shown in FIG. 2, the alpha-axis current component i under the actual stationary two-phase coordinate system is obtained through Clarke transformation_αBeta axis current component i_βAnd the alpha-axis current component i under the actual static two-phase coordinate system is measured_αBeta axis current component i_βOutput to stator flux linkage and torque estimation module while passing alpha axis current component i_αBeta axis current component i_βThe output is given to the rotating speed estimation module;

the Clarke transformation is to transform each physical quantity of a three-phase static coordinate system into a two-phase static coordinate system, the synchronous reluctance motor is a complex system with multivariable, strong coupling and nonlinearity, and in order to realize the decoupling control, the Clarke transformation is introduced: stator current i in three-phase stationary coordinate system_a、i_b、i_cAre different by 120 DEG and satisfy i_a+i_b+i_c0, according to three-phase magnetic motionThe principle that the potential is equal to the two-phase magnetomotive force can convert the three-phase current i_a、i_b、i_cProjected to a two-phase current i_α、i_βThe α axis and the a axis coincide, and the transformation matrix is expressed by the following equation (29):

step 3, the three-phase rectifier/inverter converts the direct-current side bus voltage value u_dcThe input is input to a stator voltage vector calculation module, wherein the direct current side bus voltage is derived from a bus supplied by the motor.

Step 4, the stator voltage vector calculation module carries out calculation according to the input tubular state information S of each switch_a、S_b、S_cAnd the voltage value u of the direct-current side bus input in the step 3_dcAs shown in FIG. 3, the alpha-axis voltage component u in the actual stationary two-phase coordinate system is obtained by Clarke transformation_αAnd a beta axis voltage component u_βAnd the alpha axis voltage component u under the actual static two-phase coordinate system_αAnd a beta axis voltage component u_βThe output is sent to a stator flux linkage and torque estimation module, and is simultaneously sent to a rotating speed estimation module;

and 5, estimating the stator flux linkage and the torque by a module according to the alpha-axis current component i in the actual static two-phase coordinate system input in the step 2_αBeta axis current component i_βAnd 4. alpha-axis voltage component u input in step 4_αAnd a beta axis voltage component u_βAs shown in fig. 4, the flux angle θ and the stator flux ψ are calculated_sAnd estimating the torque T_eAnd outputting the magnetic chain angle theta to a voltage vector selection table to output the stator magnetic chain psi_sOutput to the third subtracter to estimate the torque T_eOutputting to a second subtracter;

stator flux linkage psi_sFlux linkage angle theta and estimated torque T_eCalculated according to the following formula:

wherein R is_sIs stator resistance, p is the pole pair number, psi_αIs a component of the stator flux linkage of the alpha axis psi in a two-phase stationary coordinate system_βIs a beta axis stator flux linkage component under a two-phase static coordinate system;

step 6, the rotating speed estimation module carries out estimation according to the alpha-axis current component i under the actual static two-phase coordinate system input in the step 2_αBeta axis current component i_βAnd 4. alpha-axis voltage component u input in step 4_αAnd a beta axis voltage component u_βCalculating to obtain an estimated rotation speed omega, and respectively transmitting the estimated rotation speed omega to the first subtracter and the flux linkage calculation module;

the calculation formula for the estimated rotation speed ω is as follows:

step 7, inputting the given motor speed omega into a first subtracter, and inputting the power factor angleInputting the data into a flux linkage calculation module; angle of power factorThe given motor speed ω is a constant that is directly input externally.

And 8, calculating by a first subtracter according to the given motor rotation speed omega input in the step 7 and the estimated rotation speed omega input in the step 6 to obtain a speed difference delta omega, and outputting the speed difference delta omega to the speed PI regulator, wherein the speed difference delta omega is as follows:

Δω＝ω*-ω (6)

and 9, calculating the actual torque T of the motor by the speed PI regulator according to the speed difference delta omega input in the step 8_e ^*And apply the actual torque T_e ^*The output is sent to a second subtracter and a flux linkage calculation module;

step 10, the flux linkage calculation module calculates the actual torque T of the motor according to the input in the step 9_e ^*Estimated rotation speed omega input in step 6 and power factor angle input in step 7As shown in fig. 5, the stator flux linkage amplitude ψ is calculated^* _sAnd the stator flux linkage amplitude psi^* _sOutputting to a third subtracter;

the implementation method of the flux linkage calculation module is as follows:

when the synchronous reluctance motor runs stably, according to a double reaction theory, the voltage equation of the motor in a steady state can be obtained without counting the iron loss of the motor as follows:

wherein u is_dIs the direct-axis voltage of the motor u_qIs motor quadrature axis voltage, R_sIs stator resistance, L_dIs a motor direct-axis inductor, L_qIs motor quadrature axis inductance, i_dFor direct shaft current of the motor, i_qFor motor quadrature current, X_qIs motor quadrature axis inductive reactance, X_dIs a direct-axis inductive reactance of the motor.

According to the inductive reactance formula:

the voltage equation (7) may be changed to:

the apparent power of the synchronous reluctance motor during operation is as follows:

S＝(u_di_d+u_qi_q)+j(u_qi_d-u_di_q) (10)

wherein j is an imaginary unit of the complex number;

in the formula (10), P is equal to u_di_d+u_qi_qRepresenting the active power of the synchronous reluctance machine, Q ═ u_qi_d-u_di_qRepresenting the reactive power of the synchronous reluctance machine:

substituting formula (9) into (11) yields:

the power factor equation is:

combining formula (12) and formula (13) to obtain:

to simplify the operation, let equation (14)

Formula (14) is rewritten as follows:

actual torque T of synchronous reluctance motor in two-phase rotating coordinate system (d-q coordinate system)_e ^*The torque equation of (c) can be expressed as:

according to the analysis, the power factor angle of the motor is measuredAnd the motor direct axis current i in the formula (14) after the estimated rotation speed omega is determined_dQuadrature axis current i of motor_qHaving a defined functional relationship when the machine is in steady-state operation, i.e. the actual torque T_e ^*At a given time, i is obtained by combining (15) and (16)_d、i_qThe following were used: stator

Then, according to the flux linkage equation (16) and the above equation (17), the derived dq-axis current is obtained, and further the stator flux linkage amplitude psi is obtained^* _sThe following formula:

wherein, T_e ^*Representing the actual torque of the synchronous reluctance machine, p the pole pair number, psi_d,ψ_qThe projection components of the flux linkage on the direct axis d and the quadrature axis q are shown.

Step 11, the second subtracter is based on the actual torque T input in step 9_e ^*Step 5 input estimated torque T_eIs calculated to obtainDifference in torque Δ T_eAnd the torque difference DeltaT is calculated_eOutput to a torque hysteresis module, wherein the torque difference Δ T_e：

ΔT_e＝T_e ^*-T (19)

Step 12, the third subtracter is used for obtaining the stator flux linkage amplitude psi input in the step 10^* _sStep 5, inputting the stator flux linkage psi_sThe stator flux linkage difference value delta psi is obtained through calculation_sAnd then combining the stator flux linkage difference delta phi_sAnd outputting to a flux linkage hysteresis module, wherein the stator flux linkage difference value:

Δψ_s＝ψ^* _s-ψ_s (20)

step 13, the torque hysteresis module inputs a torque difference value delta T according to the step 11_eOutputting a torque control signal ST through the hysteresis comparator by the hysteresis comparator, and outputting the torque control signal ST to a voltage vector selection table;

for torque control, the method is implemented by using a hysteresis comparator, and the functional block diagram of the method is shown in fig. 6, wherein the meaning of a torque control signal ST is as follows: when ST is-1, reducing the electromagnetic torque; when ST is 0, the torque remains unchanged; when ST is 1, the electromagnetic torque is increased.

Step 14, the flux linkage hysteresis module outputs a flux linkage control signal SF through the hysteresis comparator according to the stator flux linkage difference value delta psi input in the step 12, and outputs the flux linkage control signal SF to a voltage vector selection table;

for the control of the stator flux linkage, the method is realized by using a hysteresis comparator, and the functional block diagram of the hysteresis comparator is shown in fig. 7. Wherein the meaning of SF is as follows: when SF is equal to 0, the stator flux linkage amplitude psi is reduced^* _s(ii) a When SF is 1, the stator flux linkage amplitude psi is increased^* _s。

Step 15, the voltage vector selection table obtains the tube state information S of each switch according to the section where the flux angle theta input in step 5 is located, the torque control signal ST input in step 13 and the flux control signal SF input in step 14_a、S_b、S_cAnd output to the stator voltage vector calculation module, and meanwhile, the tubular state information of each switch is usedS_a、S_b、S_cAnd controlling the switching state of the three-phase rectifier/inverter so as to realize the operation of the synchronous reluctance motor.

Examples 2,

The synchronous reluctance motor is based on the direct torque control system of the variable magnetic linkage of the optimum magnetic linkage angle, according to the optimum power angle under different rotational speeds, combine the electromagnetic torque equation to obtain the magnetic linkage amplitude under different torque states, and adjust in real time according to the running state of the motor, reduce the system loss, make the motor run under the maximum power factor, the difference with embodiment 1 only lies in:

the flux linkage calculation module in embodiment 1 is divided into an optimal flux linkage angle calculation submodule and an optimal flux linkage angle-based flux linkage calculation submodule, and accordingly, the input of the optimal flux linkage angle-based flux linkage calculation submodule is connected to the output of the speed PI regulator and the output of the optimal flux linkage angle calculation submodule respectively, the output of the optimal flux linkage angle-based flux linkage calculation submodule is used as the output of the flux linkage calculation module, the input of the optimal flux linkage angle calculation submodule is connected to the output of the rotation speed estimation module, and the remaining modules and the connection relations are consistent, as shown in fig. 8;

the method for controlling the variable magnetic chain direct torque control system based on the optimal magnetic chain angle by utilizing the synchronous reluctance motor specifically comprises the following steps:

step 1, same as example 1, step 1;

step 2, same as example 1, step 2;

step 3, same as example 1, step 3;

step 4, same as example 1, step 4;

step 5, same as example 1, step 5;

step 6, same as example 1, step 6;

step 7, inputting a given motor rotating speed omega into a first subtracter, wherein the given motor rotating speed omega is a constant directly input from the outside;

step 8, same as example 1, step 8;

step 9, same as example 1, step 9

Step 10, the flux linkage calculation module obtains through calculationStator flux linkage given value psi^* _sAnd outputting the data to a third subtracter, wherein the specific process is as follows:

step 10.1, the optimal flux linkage angle calculation submodule calculates the optimal flux linkage angle theta according to the input estimated rotating speed omega^*And the optimum flux linkage angle theta is determined^*And outputting the magnetic linkage angle to a magnetic linkage calculation submodule based on the optimal magnetic linkage angle, wherein the optimal magnetic linkage angle calculation submodule is realized by the following method:

for each control cycle, the torque is given by the rotational speed PI controller and can be regarded as a constant, and the stator flux linkage amplitude ψ at this time^* _sThe flux linkage amplitude psi at the stator can be obtained as shown in equation (21) in relation to the flux linkage angle theta^* _sAnd the magnetic chain angle theta, one variable is determined, and the other variable is determined.

L in the formula (21)_d、L_qRespectively representing direct axis and quadrature axis inductances of the motor; p represents the number of pole pairs; t is_eFor estimated torque of the motor, #^* _sIs the stator flux linkage amplitude of the motor.

When the synchronous reluctance motor operates stably, the direct-axis voltage and the quadrature-axis voltage are kept unchanged, and the formula is as follows:

the power equation is:

formula (22) is substituted for formula (23) and is obtained from the relationship between the stator flux linkage amplitude and the d and q axes:

wherein R is_sRepresenting the stator resistance;

the power factor equation is:

substituting the equations (24) and (25) into a power factor equation (26) to obtain a relation between the power factor and the rotation speed and the flux linkage angle:

r in the formula (27)_sRepresenting stator resistance, theta is magnetic chain angle, omega is estimated rotation speed of motor, L_d、L_qThe direct-axis inductance and the quadrature-axis inductance of the motor are respectively represented, and p represents the pole pair number.

It can be seen that the power factor has a defined functional relationship with the flux linkage angle theta when the motor is operating in a steady state, i.e. at steady stateIn other words, when the rotational speed reaches the steady state, there is always a corresponding flux linkage angle θ such that the power factor reaches the maximum, and the power factor obtained according to equation (27) is related to the flux linkage angle θ as shown in fig. 9.

The flux linkage angle theta corresponding to the maximum power factor is substituted into the formula (28) to obtain the optimal power angle theta^*Corresponding stator flux linkage amplitude:

according to the analysis, the synchronous reluctance motor is controlled by a variable flux direct torque control system based on the optimal flux angle, and flux amplitude is given in two stages according to the running state of the motor.

First, the optimal flux linkage angle θ can be found from the equations (27) and (28)^*The method is obtained under the condition that the motor operates stably, so a constant flux linkage amplitude direct torque control strategy is still needed in the starting stage of the motor, the motor operates at a rated torque, and the maximum torque is output to overcome an inertial load and accelerate the motor to a given operating state, so that the characteristic of rapidity of torque control is kept; secondly, when the motor runs to a steady state, the corresponding maximum flux linkage angle at different given speeds is obtained through calculation according to a formula (27), and then a variable flux linkage amplitude control strategy based on the optimal flux linkage angle is adopted.

Step 10.2, the flux linkage calculation submodule based on the optimal flux linkage angle inputs the actual torque T of the motor according to the input_e ^*Optimal flux linkage angle theta^*The stator flux linkage amplitude psi is obtained by calculation^* _sAnd the stator flux linkage amplitude psi^* _sOutputting to a third subtracter;

step 11, same as step 11 of example 1;

step 12, same as example 1, step 12;

step 13, same as example 1, step 13;

step 14, same as step 14 of example 1.

Experiment 1:

a synchronous reluctance motor variable flux linkage direct torque control system based on a power factor angle is simulated as in example 1. The synchronous reluctance motor of example 1 was simulated under different load conditions (no load, half load, full load) at given speeds of 100rpm, 1000rpm, 1500rpm, 3000rpm for a variable flux linkage direct torque control (PFA-DTC) system based on power factor angle, and was analyzed in comparison with the conventional constant flux linkage direct torque control (conventional DTC), and the simulation results are shown in table 1 below.

TABLE 1 comparison table of the present method and the conventional DTC startup simulation data

As can be seen from table 1, the stator flux amplitude of the conventional DTC remains unchanged during the whole operation process, while the variable flux direct torque control (PFA-DTC) system of the synchronous reluctance motor of embodiment 1 based on the power factor angle can perform real-time adjustment of the flux amplitude according to the change of the torque. Compared with the traditional DTC, the variable flux direct torque control (PFA-DTC) system based on the power factor angle of the synchronous reluctance motor in the embodiment 1 reduces the torque ripple in a steady state, particularly greatly reduces the torque ripple under the condition of no load or light load, reduces the steady state rotating speed fluctuation, improves the power factor of the motor in steady state operation, and achieves the purpose of the invention.

Experiment 2:

in embodiment 2 of the method, a synchronous reluctance motor based on an optimal flux linkage angle based flux linkage amplitude theory based on an optimal flux linkage angle provided by a variable flux linkage direct torque control system based on an optimal flux linkage angle can obtain flux linkage amplitudes in different torque states by combining an electromagnetic torque equation according to optimal power angles at different rotating speeds, and real-time adjustment is performed according to the motor operating state, so that the motor operates under the maximum power factor. In the range of 3000rpm of rated rotation speed of the synchronous reluctance motor, no-load starting, half-load starting and full-load starting simulation are performed on the variable magnetic chain direct torque control of the synchronous reluctance motor based on the optimal magnetic chain angle, so that the steady-state operation of the motor is realized, and the simulation result is shown in the following table 2.

Table 2 comparison table of the simulation data of this embodiment 2 and the conventional DTC start-up

As can be seen from table 2, in example 2, flux linkage amplitude is given compared with the optimal flux linkage angle at different rotation speeds of the conventional DTC, so that the variable flux linkage amplitude control scheme can maintain a higher power factor under different loads.

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.